script does not work. have to rename files to all lowercase, without underscore and still has issues

[skiwheelr]

replace script has a SED error code R and I can't figure out why.
nothing except the four lines are edited prior to running.

➜  docsify git:(master) ✗ ./replace.sh 
PATTERN
s/DocsifyJS Template/Flop Hub/g
s/MichaelCurrin\/docsify-js-template/flophub\/docsify/g
s/docsify/docsifyjs-template/g
s/Starter template for a markdown-based docs site/A two-sided hardware marketplace built on Kubernetes/g
sed: 1: "README.md": invalid command code R
➜  docsify git:(master) ✗ cd ..